Electric fuse



Sept- 6, 1932 H. T. BUssMANN 1,875,415 ELECTRIC FUSE Filed Nov. 9, 1923 6 f@ E i f@ Patented Sept. 6, 1932 PATENT OFFICE HENRY T. BUSSMANN, F ST. LOUIS, MISSOURI ELECTRIC FUSE Application illed November 9, 1923. Serial No. 673,756.

My invention relates to electric fuses and refers particularly to that ty e of fuse known as the 'renewable knife blade contact type, and the object of my invention is to provide 6 a fuse that will be safe in operation, yet of simple design, permitting of low manufacturing costs, and' capable of being renewed indefinitely.

These advantages of m invention will be more readily understood y referring to the accompan ing drawing which shows a preferred embodiment of my invention. Fig. 1 shows a cross sectional view of my fuse. Fig. 2 is a view of a terminal with washer attached thereto. Fig` 3 is an end view of the closure.

As shown in the drawing, 5 is a casing having attached thereto the closure fitting 6 closing one end of the casing and the ring 7 attached to the other end. The fuse link 8 which may be of any desired type is attached to the terminals 9, 10, by bolts 15, 15 or in any other manner. The terminal 9 has attached thereto washer 11 and is passed through the fitting 6 at the end of the casing. The terminal 10 has attached thereto a washer 12 and the closure washer 13 which is held in position by the cap 14. The terminal support 2O serves to hold the two terminals in spaced relation to each other.

The vapor generated by the blowing of an electric fuse, if allowed to escape too freely from the enclosure, will ignite readily inflammable material that might be near the fuse. In addition to this, high pressure in the fuse case helps to extinguish the arc, and it is therefore desirable to hold the vapor in the fuse casin At the same time, this pressure must be ept down to what the en- "o closure can safely hold. In other words, a

venting system in an electric fuse must hold enough pressure to quench the arc, but release enough to prevent rupture of the casing without igniting readily inflammable material that might be near the fuse.

The washer 12 has a knurled, grooved or interrupted surface as shown at 16 and is held against the inner surface of the closure washer 13 which has an opening at the terminal to permit the escape of the vapor generated on the blowing of the fuse. In this way an indirect exit for the vapor is provided so that it is cooled sufficiently before being allowed to escape, so as to prevent ignition of readily inflammable material that might be near the fuse.

To also definitelycontrol the amount of vapor permitted to escape, so as to hold enough vapor so that its pressure will help extinguish the arc, and yet permit enough to escape so as to prevent rupture of the case, I prefer to make the opening in the closure washer so that part of the periphery of such opening fitsv closely around the terminal as shown at 18, 18 and the balance of the periphery of this opening is held away from the terminal so as to allow a predetermined .space between the terminal and the closure as shown at 19, 19 for the exit of a limited determined amount of vapor.

The washer 11 attached to terminal 9 may be of the same design as the washer 12. The terminal support or bridge device 20 attached to both terminals holds the terminals in spaced relation to each other; therefore, when the cap 14 is screwed down on the Washer 13 which is attached to terminal 10, a pressure is exerted on terminal 9 and the washer 11 is thereby tightly held against the inner surface of the closure fitting 6 to accomplish the results set forth.

From this it can be readily seen that I have provided in a simple manner a positive means for accomplishing the desired results. It is obvious that a number of variations from the exact description are permissible to accomplish these results and what I claim is:

, 1. In a fuse, a casing, a terminal, a closure disc attached to the terminal, means for holding the closure disc to the casing, a fuse link, means for connecting the link to the terminal, the closure disc having the aperture within which the terminal is fitted so arranged that part of the periphery of the aperture is fitted tightly on the terminal and the balance of its periphery is held in a fixed positionaway from the terminal so as to allow a predetermined spacc between the terminal and the closured disc for the exit of a limited dcter- 10 gan mined amount oit the vaper generated on blowing the inse link.,

2. ln a inse, a casing, a closure, means for holding the closure to the casing, a termina-, said closure having an opening within which the terminal is removably positioned, a fuse link, neans for connecting the link to the terminal, a washer attached to the terminal, grcoves in the outer face of said washer to correl the exit et vapor, said washer having a diameter extending beyond the opening in closure when the terminal is positioned th rein and coacting with said closure to prevent the direct exit of vapor from the fuse.

3, in a Jfuse, a casing, a closure, means for holding the closure to the casing, a termina-, a fuse link, means tor connecting the link to the terminal, a washer attached to the terminal and coacting with the closure to provide indirect exit for the vapor generated on blowing of the fuse, the closure having an aperture to receive the terminal, said aperture having part ot its periphery so arranged as to lit tightly on the terminal and to hold the balance of its periphery in a fixed position away from the terminal so as to allow a predetermined space between the terminal and the closure for the exit of a limited determined amountoi' vapor.

Ll. ln a fuse, a casing, a closure, means for holding the closure to the casing, a terminal, a iiuse link, means for connecting the link to the terminal, a washer attached to the terminal, grooves in said washer to control the exit ot vapor, said washer coacting with the closure to provide an indirect exit for vapor, the closure having an aperture to receive the terminal, said aperture having part of its periphery so arranged as to littightly on the terminal and to hold the balance of its periphery in a fixed position away from the terminal so as to allow a predetermined space between the terminal and the closure for the exit of a limited determined amount of vaporE 5. in a renewable fuse, a casing, a terminal, a closure tting threadedly secur-ed to the casing having an opening within which the terminal is removably positioned, a member positioned by the terminal and tightly fitting thereon, having a tace of a diameter extending beyond the opening in the closure iitting when the terminal is positioned therein, said .member being adapted to be held against the inner face of the closure lit-ting and coacting with the closure fitting to prevent the exit of vapor from the interior of the fuse except for such vapors as might pass between the member and the closure litting and be directed toward the terminal, when the terminal is positioned in said opening.

6. In a renewable fuse, a casing, a terminal, a fuse link, a closure fitting threadedly secured to the casing having an opening within which the terminal is removably positioned, a member positioned by the terminal and tightly litting thereon, having a face of a diameter extending beyond the opening in the closure iitting when the terminal is positioned therein, said member being adapte to be held against the inner face ol1 the closure fitting and coacting with the closure fitting to prevent the exit of vapor from the interior ot the fuse except for such vapors as might pass between the member and the closure litting and be directed toward the ter: minal, when the terminal is positioned in s aiu opening and means independent of the link for holding said member to the closure fitting.

7. ln a renewable fuse, a casing, a terminal, a closure litting threadedly secured to the casing having an opening within which the terminal is removably positioned, a'inember positioned by the terminal and tightly fitting thereon, completely closing the opening in the closure iitting except for the terminal projecting therethrough and closely' abutting a substantial area or' the inner surtace of the closure fitting immediately adjacent to all sides of: the opening to prevent the exit of vapor from the interior of the fuse eX- cept for such vapors as might pass between the member and the closure fitting and be directed toward the terminal.

8. In a renewable use, a casing, a fuse structure comprising flat blade terminals and a bridge device, a closure attached to the Cas-- ing having an opening for one ot said tei'- mina'ls to be passed therethrough, a member positioned by said terminal and tightly titting thereon, completely closing the opening in the closure except for the terminal projecting therethrough and closely abutting a substantial area of the inner surface et the closure immediately adjacent to all sides of the opening to prevent the exit of vapor from the interior of the fuse except for such vapors as might pass between the member and the closure and be directed toward the terminal; said bridge device serving to hold the terminals in spaced relation to each other and holding the member in close abutment with the closure.

9. In a renewable fuse, a casing, a closure means for holding the closure to the casing, said closure having an opening for a. terminal to be passed therethrough, a link connected to said terminal, a member positioned by the terminal having a face adapted to be held against the inner face of the closure to prevent the direct exit of vapor from the fuse when the terminal is positioned in said opening, a portion of one of the abutting faces being interrupted to control the indirect exit of vapor and means independent of the link for holding said member against the inner face of the closure.

10. In a renewable fuse, a casing, a closure,

means for holding the closure to one end of the casing, a fuse Structure comprising fiat blade terminals and a bridge devlce; a member attached to one of said terminals having its outer face adapted to be placed in abutting relation with the inner face of the closure, a

portion of one of said faces being interrupted c to provide an indirect exit for vapor between said faces; said bridge device serving to hold the terminals in spaced relation to each other and holding the member in close abutment with the closure.

HENRY T. BUSSMANN. 

